| Summary: | Evidence of epidemicity of nasopharyngeal carcinoma (NPC) was sought in Greenland Inuits, who have a high incidence of this cancer, by examining the births of NPC cases for evidence of clustering in time and space. Births of cases were concentrated in autumn and winter. Fifty-four cases were analysed, and a two-fold excess of clustering within one year was observed, both within single districts and between adjacent districts. This excess was not significant at the 5 % level; about 90 cases would have been required to confirm the observed effect at this level of significance. It is suggested that a search for space-time clustering of NPC cases in larger high-risk populations might prove more fruitful. Nasopharyngeal cancer is a rare tumour in most populations, with an annual incidence below 1 per 100,000, but in various ethnic Chinese populations the annual incidence rate is ten to twenty times higher, and reaches 29 per 100,000 in Cantonese living in Singapore (Shanmugaratnam, 1982). Most nasopharyngeal carcinoma (NPC) in these high-risk areas is undifferentiated squamous carcinoma (WHO type II and III) (Clifford & Beecher, 1964;
|
|---|